I hunt sys admins 2.0

“I Hunt Sys Admins”
(U) Will
@harmj0y
Version 2.0

$ whoami
● Security researcher and red teamer for the
Adaptive Threat Division of Veris Group
● Co-founder of the Veil-Framework and
founder of Veil’s PowerTools
● Cons:
o Shmoocon ‘14: AV Evasion with the Veil Framework
o Defcon ‘14: Veil-Pillage: Post-exploitation 2.0
o Derbycon ‘14: Passing the Torch: Old School Red
Teaming, New School Tactics?

What this is
● Ways to hunt for target users on Windows
domains
● Ya really, that’s it
● Will cover as many tools and technique for
doing this as I have time for

● Setting the stage
● Existing tools
o psloggedon.exe, netsess.exe, PVEFindADUser.exe,
netview.exe, Nmap, smbexec, Veil-Pillage
● Domain data sources
o homeDirectory, profilePath, event logs, email
headers, SPNs
● PowerShellz
o Sidenote: PowerShell WinAPI access
o PowerView
tl;dr

Setting the Stage
● This talk is from the “assume breach”
perspective
o i.e. assume foothold/access to a Windows domain
machine
● I’m also going to assume you know (more or
less) what users you’re targeting
● PowerShell methods are going to heavily
rely on PowerView
o https://github.com/veil-framework/PowerTools

User Hunting: Lateral Spread
● Most common:
o If you have a privileged account, or local admin
account, you want to figure out where high value
users are logged in
● Hunt -> pop box -> Mimikatz -> profit
● Knowing what users log in to what boxes
from where can give you a better
understanding of a network layout and
implicit trust relationships

User Hunting: Post DA
● Red teaming isn’t about access, it’s about
data and showing impact!
● Once you get privileged access (like domain
admin) there are likely specific targets you
might want to go after
● Think incident response teams, CEOs, the
linux team, database admins, etc.

Where my sysadmins at?
Finding your prey

Existing Tools
● Several tools have been written that allow
you to figure out who’s logged in where
● I’ll cover what’s already out there, including
the positives/negatives for each
● “Offensive in depth”
o You always want multiple ways of achieving the
same objective

● Component of Microsoft’s Sysinternals
o “...determines who is logged on by scanning the
keys under the HKEY_USERS key.”
o “To determine who is logged onto a computer via
resource shares, PsLoggedOn uses the
NetSessionEnum API.”
● Needs remote registry access to determine
who’s logged in
o i.e. admin privileges on a remote machine
http://technet.microsoft.com/en-us/sysinternals/bb897545.aspx
psloggedon.exe

netsess.exe
● Component of
http://www.joeware.net/freetools/
● Utilizes the NetSessionEnum API call
o http://msdn.microsoft.com/en-
us/library/windows/desktop/bb525382(v=vs.85).aspx
● Think a version of “net session” that works
on remote machines!
o great for targeting file servers :)
o no admin privs needed!

PVEFindADUser.exe
● Tool released by corelanc0d3r in 2009
● “Helps you find where AD users are logged in”
o Can also check who’s logged into specific machines
● But “...you also need to have admin access on
the computers you are running the utility
against.”
https://www.corelan.be/index.php/2009/07/12/free-tool-find-where-ad-users-are-logged-on-into/

netview.exe
● Rob Fuller’s (@mubix) netview.exe project,
presented at Derbycon 2012, is a tool to
“enumerate systems using WinAPI calls”
● Finds all machines on the network,
enumerates shares, sessions, and logged in
users for each host
o And now can check share access, highlight high
value users, and use a delay/jitter :)
o and also, no admin privs needed!
https://github.com/mubix/netview

Nmap
● If you have a valid domain account, or local
account valid for several machines, you can
use smb-enum-sessions.nse
● Don’t need to have admin privileges!
nmap -sU -sS --script smb-enum-
sessions.nse --script-args
'smbuser=jasonf,smbpass=BusinessBus
inessBusiness!' -p U:137,T:139
192.168.52.0/24
http://nmap.org/nsedoc/scripts/smb-enum-sessions.html

Smbexec
● Awesome post-exploitation framework built
on top of patched Samba binaries
● The enumeration/checkda module can
check machines for domain admin
processes/sessions on particular targets
● However:
o requires local admin on the target machine
o only can target domain admins

Veil-Pillage
● Veil-Pillage is a post-exploitation framework
conceptually similiar to Smbexec
● The enumeration/domain/group_hunter
and enumeration/host/user_hunter
modules will do the same tasklist and
qwinsta process to hunt for specific target
groups
● However:
o requires local admin on the target machine
o but can target more than just domain admins

Domain Data Sources
“It’s a feature”

Active Directory Sources
● There are a few components of Active
Directory user objects that warrant interest
● homeDirectory
o path to a user’s auto-mounted home directory
● profilePath
o path to a user’s roaming profile
● Why?
o Enumerating remote sessions against common
network servers lots of people use gives an
excellent mapping of what users are where

Event Logs
● Sometimes you have DA, but need to target
specific users (think the IR team :)
● If you can query the event logs on a domain
controller, you can extract:
o logon type (interactive/network), account name,
source network address
● @sixdub rolled this into a PowerShell script,
which has since been incorporated into
PowerView, more on this later
http://sixdub.net/2014/11/offensive-event-parsing-bringing-home-trophies/

Email Headers
● If you have access to someone’s email
(Mimikatz+OWA, etc.) internal headers can
provide a wealth of information
● Search for any chains to/from target users,
and examine headers for given email chains
● If the “X-Originating-IP” header is present,
you can trace where a user sent a given
email from

Service Principal Names
● SPNs aren’t just for machines
● Registering a service to run on a machine
under a particular user account will register
that machine/service for that user in AD
o Makes a great place to check for users, all with a
single AD query
● Scott Sutherland (@_nullbind) has a great
article on this:
o https://blog.netspi.com/faster-domain-escalation-
using-ldap/

Manual Checks
● To find your targets:
o net user “Domain Admins” /domain
● To find your file servers:
o AdFind.exe -f "samAccountType=805306368" attr
homeDirectory | findstr /c:"homeDirectory"
● To find where your targets are:
o NetSess.exe FILESERVER

Wrapping in VBScript
● You can wrap some of these tools in some
basic VB script to automate it all up
● Run tool, filter for target users, etc.
● But why use VBScript, when you have...

PowerShell
“Microsoft’s Post-Exploitation Language”
-@obscuresec

PowerShellz
● PowerShell has some awesome AD hooks
and has various ways to access the lower-
level Windows API
● You can also access the lower-level Win32
API for interesting functions
○ NetSessionEnum for user sessions
○ NetWkstaUserEnum for logged on users
● Thanks @mattifestation for lots of ways to
access the underlying API functions!

Enumerating Targets
● PowerView has several functions that can
help you enumerate target users and hunt
them down
● Finding targets:
o Get-NetGroups *wildcard* will return groups
containing specific wildcard terms
o Get-UserProperties will extract all user property
fields
 often interesting field names!
o Invoke-UserFieldSearch will search particular user
fields for wildcard terms

Invoke-UserHunter
● Flexible function that:
o queries AD for hosts or takes a target list
o queries AD for users of a target group, or takes a
list/single user
o uses Win32 API calls to enumerate sessions
(NetSessionEnum) and logged in users
(NetWkstaUserEnum), matching against the target
user list
● Can also check to see if you have local
admin access on targets
o but no admin privs needed to get good info!

Invoke-UserView
● Several times on engagements we found
ourselves rerunning Invoke-UserHunter in
order to re-hunt for specific users
● This creates a lot of unnecessary noise
● Invoke-UserView will run the exact same
functions/checks that Invoke-UserHunter
does, but preserves all output for later
processing

Invoke-StealthUserHunter
● Uses an old red teaming trick
1. Queries AD for all users and extracts all
homeDirectory fields to identify likely domain file
servers
2. Runs NetSessionEnum against each file server to
enumerate remote sessions, matching against target
user list
● Gets reasonable coverage with a lot less
traffic than UserHunter
o and again, no admin privs needed

Invoke-UserProcessHunter
● Utilizes the newly christened Get-
NetProcesses
o this function makes it easy to enumerate running
processes on remote machines
● You will need admin privileges on the
machines you’re enumerating
● Invoke-UserProcessHunter wraps this all
up into a weaponized form

Invoke-UserEventHunter
● Sometimes you have DA, but need to target
specific users (think the IR team :)
● Domain controller event logs make it trivial to
track down domain users, provided you have
domain admin access
● Get-UserLogonEvents implements
@sixdub’s work on offensive event parsing
o Invoke-UserEventHunt rolls this all into a
weaponized form

Shameless Sidebar
● Want to research cool stuff like this?
● Want to work with 13 x OSCPs and 3 x
OSCEs?
● Want to do some sweet red teaming?
● Hit me up to join Veris Group’s Adaptive
Threat Division

Questions?
● Contact me:
o @harmj0y
o will [at] harmj0y.net
o harmj0y in #veil and #armitage on Freenode
● Read more:
o http://blog.harmj0y.net
o https://www.veil-framework.com
● Get PowerView:
o https://github.com/Veil-Framework/PowerTools

I hunt sys admins 2.0

More Related Content

What's hot (20)

Similar to I hunt sys admins 2.0 (20)

More from Will Schroeder (19)

Recently uploaded (20)

I hunt sys admins 2.0